The present invention relates to an oil separator that separates oil contained in blow-by gas of an internal combustion engine.
An oil separator that is attachable to a side face of a cylinder block, for example, is known as this kind of oil separator (for example, see Japanese Laid-Open Patent Publication No. 2006-70766). The oil separator disclosed in the aforementioned document includes a case that is attachable to a side face of a cylinder block, and a partition plate that is provided in a protruding manner from a side wall of the case and vertically partitions the space inside the case. The oil separator also includes an introduction passage provided in the bottom wall of the case, and a discharge passage provided in an upper portion of a side wall of the case. The introduction passage introduces blow-by gas from inside a crankcase into the case. The discharge passage discharges blow-by gas from inside the case to an intake passage. The partition plate has an inclined wall portion and a suspended wall portion. The inclined wall portion extends from a side wall of the case and inclines with respect to the horizontal direction so as to be located progressively downward in the direction away from the side wall. The suspended wall portion extends in the downward direction from the distal end of the inclined portion. A constriction passage for increasing the flow velocity of blow-by gas is provided in a vertically extending manner through the inclined wall portion of the partition plate. Further, in an upper portion of the partition plate inside the case, a collision plate is provided that extends from a side wall of the case and against which blow-by gas that has passed through the constriction passage collides.
In the aforementioned oil separator, blow-by gas is introduced into the case through the introduction passage, and passes through the constriction passage and flows in the upward direction. Oil mist contained in the blow-by gas collides with and collects on the collision plate, and is thereby separated from the blow-by gas. Further, the oil that has collected on the collision plate drips onto the inclined wall portion under its own weight, and passes through a gap between the suspended wall portion and a wall portion of the case and flows downward onto the bottom wall of the case. The oil that has flowed downward in this manner is discharged to the outside of the case from the introduction passage.
In the oil separator disclosed in the aforementioned document, in order to discharge oil that has been separated by means of the collision plate to the outside of the case, the partition plate having the inclined wall portion and the suspended wall portion is provided. Consequently, there are disadvantages in that the structure of the oil separator is complicated by the presence of such a partition plate and collision plate, and the size of the oil separator is large.